The present invention relates to a movable onvehicle large display device which can be employed for events such as a horse race, a bicycle race, a concert, a speech meeting and the like, all of which provide many people with image information in a large place.
Such an on-vehicle large display device is installed on the bed of a large vehicle, is moved to a place of a concert, a speech meeting or the like together with the vehicle and is installed therein.
FIG. 1 shows the arrangement of a conventional on-vehicle large display device. In FIG. 1, reference numeral 1 denotes a large vehicle, and reference numeral 2 denotes a display device installed on the bed 7 of the vehicle 1. The display device 2 comprises an upper screen 4 which can be vertically be moved by a vertical extension hydraulic unit 3, and a lower screen 6 which can be horizontally be moved by a horizontal extension hydraulic unit 5 (the left and right in the direction of movement of the vehicle are considered as the front and rear, respectively, hereinafter).
The operation of the device is described below.
FIG. 2A shows a housing state where the upper screen 4 is disposed in front of the lower screen 6. The display device 2 in this housing state is carried by the vehicle 1. When the display device 2 is constructed, the rod 3a of the vertical extension hydraulic unit 3 is first extended so that the upper screen 4 is upwardly moved, as shown in FIG. 2B. The lower screen 6 is then pushed forward by the rod 5a of the horizontal extension hydraulic unit 5 so as to be disposed below the upper screen 4, as shown in FIG. 2C. The upper screen 4 is moved slightly downward by the vertical extension hydraulic unit 3 so as to be mounted on the lower screen 6 to complete the assembly, as shown in FIG. 2D. The procedure for housing the assembled display device is reverse to that described above.
However, there is a demand for increasing the size of such an on-vehicle large display device. The conventional on-vehicle large display device has a limit with respect to an increase in the size thereof because of the assembly of the upper and lower screens.